1. Field of the Invention
Embodiments described generally relate to systems and methods for protecting subterranean structures. More particularly, embodiments described relate to systems and methods for protecting subterranean structures against external stresses.
2. Description of the Related Art
Ice in the Arctic and sub-Arctic areas pose a substantial risk to underwater pipelines. As ice drifts into shallow waters, water currents, wind, and other masses of ice continue to push the ice into waters shallow enough that the ice gouges into the bottom of the body of water. Ice gouging has been observed in many parts of the world, as far south as the northern Caspian, Lake Erie, and offshore Sakhalin. The gouges can be large and deep with breadths more than 100 meters and depths more than 7 meters. The force exerted by the ice to create such large gouges can easily reach 100 MN. If this level of force were applied to a seabed structure, such as a pipeline or wellhead, substantial damage could occur.
Protection of underwater pipelines, wellheads, and other equipment from ice gouges is extremely difficult and usually economically impractical. Currently pipelines and other underwater structures are often buried at a depth of 1 to 2 meters to protect the structures against fishing gear, dragging anchors, hydrodynamic forces, and seabed level changes. However, those depths are insufficient to protect an underwater structure against the forces exerted on the floor bed of a body of water. Furthermore, burying an underwater pipeline, wellhead, or other structure to depths necessary to reduce or eliminate potential damage from ice gouging can be economically impractical or physically impossible, as such equipment does not exist for burying structures in waters much deeper than about 20 meters.
There is a need, therefore, for more efficient systems and methods for protecting subterranean structures.